Hard Rock Concrete Supplies carries a full range of supplies for the concrete industry. Our range of products includes; Sealers, Cure & Seals, Rebar (Steel and GFRC), Insulation, Support Brackets, Weeping Tile, Patching and Repair Materials; as well as hand and power tools.
Our team prides itself on our customer service, product knowledge, and wide range of quality products and would love the opportunity to talk with you about all of your concrete needs. 

Primer T

SKU: 366917
Regular price $30.49


Primer T is a low-VOC, magenta-colored, water-based acrylic primer that enhances the performance and adhesion of self-leveling underlayments (SLUs) on nonporous and porous substrates. Suitable for a wide variety of substrates, Primer T combines excellent versatility with easy, low-odor application.

  • One-component, versatile primer for a wide variety of substrate conditions
  • Single-coat application for faster turnaround and lower installation costs
  • Easy handling and application
  • Magenta-colored for easier coverage control
LEED v4 Points Contribution LEED Points
Health Product Declaration (HPD)*...........................Up to 2 points
* Using this product may help contribute to LEED certification of projects in the category shown above. Points are awarded based on contributions of all project materials.


Additional Green Certifications

  • CRI Green Label Plus #GLP54548. Refer to the CRI's Website at www.carpet-rug.org for additional information.
  • Living Building Challenge (LBC) Red List Free: This product has been verified per the most current Red List on the LBC's Website.


  • Use Primer T when applying a self-leveling underlayment on properly prepared suitable substrates.
  • Interior residential (apartments, condominiums and homes)
  • Interior commercial (office buildings, hotel rooms/hallways, restaurants and cafeterias)
  • Interior heavy commercial (hotel lobbies, convention centers, airports, shopping malls, grocery stores and department stores)
  • Interior institutional (hospitals, schools, universities, libraries and government buildings)


  • Do not install over any substrates containing asbestos.
  • Substrate and ambient temperatures must be between 50°F to 90°F (10°C to 32°C).
  • In all cases, the surface temperature of the prepared concrete slab must be at least 5 degrees F (2,8 degrees C) above the dew point to avoid condensation on the concrete surface as Primer T dries.
  • For moisture limits on this primer, refer to the moisture limits of the product to be applied over it.
  • For use only in dry, interior environments. Do not apply on wet substrates.
  • Use undiluted over moisture-stable, exterior-grade plywood.
  • Use undiluted over dense, nonabsorbent surfaces, such as epoxy moisture barriers, floor-covering adhesive residue, and ceramic tile and VCT.


  • Properly bonded tile, stone and VCT
  • Properly installed 100%-solids epoxy moisture barriers
  • Epoxy terrazzo, cement terrazzo and poured epoxy flooring
  • Cement backer units (CBUs)
  • Substrates with traces of well-adhered, water-resistant glue (cutback adhesive, floor-covering adhesive or polyurethane adhesive)
  • Dimensionally stable exterior-grade plywood
  • Sound and stable concrete substrates, whether smooth and nonabsorbent or profiled and absorbent
  • Use over gypsum-based SLUs that are free of gypsum dust before application of cementitious or gypsumbased SLUs.

Consult MAPEI’s Technical Services Department for installation recommendations regarding any substrates and conditions not listed.


  • All substrates must be interior, structurally sound, dry, solid and stable.
  • Mechanically prepare existing ceramic, quarry and porcelain tile, as well as cement terrazzo.
  • Thoroughly clean all surfaces of any substance that could interfere with the bond of the installation material, including dirt, dust, paint, tar, asphalt, wax, oil, grease, latex compounds, sealers, curing compounds, form release agents, laitance, loose toppings, foreign substances and poorly bonded adhesive residues.
  • Do not acid-etch surfaces before applying Primer T.
  • When applying MAPEI underlayments to plywood flooring or oriented strand board (OSB), the installation specifics (finished flooring, load, use and/or deflection) may require the use of MAPEI’s Mapelath™ or diamond mesh (meeting the requirements of ASTM C847) on

top of the primed surface before application of the underlayment. In all cases, one can anticipate better performance when utilizing lath, particularly over OSB. Refer to Mapelath’s current Technical Data Sheet for installation instructions. Differential or excessive movement within a plywood substrate may lead to hairline cracks at plywood joints.


Before product use, take appropriate safety precautions.

Refer to the Safety Data Sheet for details.

1a. Over nonabsorbent surfaces and wood: Apply Primer T undiluted. (Add no water; no mixing is required.)

1b. Over porous, absorbent surfaces (typically absorbent, profiled concrete substrates): Dilute Primer T with water at a ratio of 1:1 to 2:1 (water to primer). Mix with water in a separate clean container with a low-speed mixer and paddle to a homogenous consistency. Do not mix at high speeds, which may cause product foaming.

1c. Over gypsum substrates: Dilute at a ratio of 2:1 (water to primer). Mix as indicated in Step 1b and apply two coats if required by visual inspection.



Read all installation instructions thoroughly before installation.

  1. Apply the product with a 3/8" (10 mm) nap roller. Ensure that the surface receives a complete, thin film of product.

2a. Nonabsorbent substrates and wood require only one coat of undiluted Primer T.

2b. Absorbent and gypsum substrates may require more than one coat of diluted Primer T to seal off the substrate and prevent substrate outgassing.

  1. The underlayment can typically be applied within 2 to 5 hours (see the “Application Properties” chart). Drying times will vary depending on the porosity of the surface, temperature and humidity. The maximum wait time from initial application is 24 hours.
  2. If the dried Primer T remains uncovered for more than 24 hours, re-apply a second, undiluted coat and install the underlayment within the correct application window (see the “Application Properties” chart). If the application window is missed again, remove the primer mechanically and start the installation on the clean substrate.


  • Clean equipment immediately with water. Mineral spirits may be used to remove primer that has dried on tools.

Product Performance Properties at 73°F (23°C) and 50% relative humidity

Labratory Tests


Solids content

43% to 45%

VOCs (Rule #1113 of California’s SCAQMD)

92 g per L

VOCs (Section 01350 of California’s CDPH)



7 to 8

Viscosity (RV2 @ 20 rpm)

1,400 cps


64.2 lbs. per cu. ft. (1,03 g per cm3)

Laboratory Tests Results

Shelf Life and Product Characteristics

Polymer type



Pourable liquid



Shelf life


2 years when stored in original, unopened packaging at 73°F (23°C) and 50% relative humidity. Protect from freezing during transport and storage.


Application Properties

Application temperature range

50°F to 90°F (10°C to 32°C)

Window for application of SLU at 73°F (23°C)

Over porous substrates: Primer T must dry for at least 2 to 3 hours (no longer than 24 hours)


Over nonporous substrates: Primer T must dry for at least 5 hours (no longer than 24 hours)

Flash point (Seta)

> 212°F (100°C)


CSI Division Classification
Cast Underlayment 03 54 00


1 U.S. qt. (946 mL)
2 U.S. gals. (7,57 L) 
Approximate Coverage*ypical Application Tool Coverage
3/8" (10 mm) nap roller
1 U.S. qt. (946 mL): 50 to 100 sq. ft. (4,65 to 9,29 m2);
2 U.S. gals. (7,57 L): 400 to 800 sq. ft. (37,2 to 74,3 m2)
* Coverage depends on the substrate profile and porosity.
Primer T TDS

Primer T SDS
Primer T Instruction Sheet